Local Variation in Egg-Capsule Size in New England Populations of Nucella lapillus (Atlantic Dogwhelk)

Abstract

Nucella lapillus (Atlantic Dogwhelk) deposits egg capsules on solid, intertidal substrates across the North Atlantic. This study investigated whether regional geographic variation or local wave-exposure affect the size of Dogwhelk egg capsules. Over 3 years, we evaluated whether Dogwhelks from wave-exposed and wave-protected sites in Massachusetts and mid-coast Maine differed in their egg-capsule size. Our results indicate that egg capsules collected from wave-exposed sites in Maine were smaller than egg capsules from wave-protected sites in Maine, but the size of egg capsules from Massachusetts did not vary with wave-exposure. These patterns in egg-capsule size coincide with Dogwhelk size from the same sites. Despite the positive correlation between the sizes of adult Dogwhelks and the egg capsules collected, wave-protected Dogwhelks from Massachusetts showed plasticity in the size of egg capsules produced but those from Maine did not. The Massachusetts Dogwhelk's greater plasticity in egg-capsule size highlights important local variation in control of reproductive investment and may accommodate fluctuations in desiccation stress and future climate change.